Thursday, April 26, 2012

Netta Smith and I made a very long trip just to see a bunch
of chickens strutting around. But these were special "chickens," and
it was worth the trip. We drove from Seattle all the way to Dubois, Idaho,
where we had reserved a blind in mid April at the edge of a Greater Sage-Grouse
lek. This species, Centrocercus
urophasianus, is the largest North American grouse. The males are not
turkey size, but at over three kilograms in weight, they are big chickens!

Males begin to assemble at display grounds, which are called
leks, in early spring, often while snow is still on the ground. Then they may
display for as long as three months. The leks can contain just a few males or
rarely up to several hundred. Males arrive at dusk and may remain through the
night, but highest activity is usually around sunrise. When fully into it, males
perform their complicated display 6-10 times/minute. Males keep the tail erect
and fanned at all times, but then at intervals they step forward and inflate their large
esophageal pouches.

The pouches swell and protrude through the snow-white neck
feathers and the whole neck and breast move up and down together with the wings
rotating forward and back. The expanded sacs make loud plops, and these sounds
dominate the auditory experience at a lek, although the loud songs of
meadowlarks often add to it. The males also make a swishing noise with their
wings and a rattle with their tail feathers, an impressive collection of
nonvocal sounds.

The smaller, duller females are not much in evidence,
but they move quietly through the lek, apparently looking for a male that
impresses them. If they find him (it may take several visits), they crouch down and copulation takes place.
Some males are outrageously successful, very few individuals accounting for
most of the matings that take place on the lek. We don't know exactly what
gives them that advantage, but it may be that some males never get to mate!

At the Dubois lek, there were over 50 males at sunrise. A
fly-by Prairie Falcon scared about half of them away with a sudden burst of
flights in all direction. Another bunch left a bit later, and the few females
present left at that point, but a dozen males stayed behind and displayed for
another hour after the sunlight hit them. The closest were 30 feet from the
blind and were wonderfully oblivious to the telephoto lenses poking out at them
and the constant click of shutters.

After the female copulates once, she has sufficient sperm to
fertilize her clutch of about eight eggs. She wanders back into the sagebrush
and builds a nest, often under a shrub, incubating the eggs and then
shepherding the young around as they grow. Males take no part whatsoever in
parental care, quite typical of grouse.

The last few birds flew away from our lek about two hours
after we arrived, leaving us with a feeling of awe at how natural selection had
molded such showy, yet precise and stereotyped, behavior the sole purpose of
which was to gain a mating opportunity.

The town of Dubois puts on a bird festival every spring,
Dubois Grouse Days. Check their website for next year's show. Reserve a blind
for yourself. You don't have to be a photographer to appreciate the spectacle,
but I would advise bringing a camera!

Tuesday, April 10, 2012

If you know the word "goldeneye" only from the book of the same name by Ian Fleming or the movie featuring James Bond, you're missing something. Goldeneyes are ducks! There are two species of goldeneyes, Common (Bucephala clangula) and Barrow's (Bucephala islandica), and they are among the most common wintering waterfowl in Puget Sound.

Male goldeneyes have black heads and backs and white sides, females brown heads and gray bodies. Their bills are short and high for a duck. Not surprisingly, they have bright yellow eyes. The males of the two species can be distinguished easily by the shape of the white spot before the eye and the relative amount of black on the back. Females are more similar, but their head shapes are different, Barrow's with a higher forehead and puffier crown. During late winter and spring, the bill of a female Barrow's turns orange, making identification easy.

Goldeneyes have relatively large heads and short necks, giving them a bull-headed look in flight. In fact, Bucephala means bull-headed. The males have big white wing patches, the females smaller patches. The wings of the males in both species whistle loudly in flight, and hunters call them "whistlers." We don't know the significance of the wing whistling.

Goldeneyes are aquatic predators, diving to the bottom to forage for invertebrate prey. Barrow's seem to specialize in bivalves, while Commons eat just about anything, including a variety of mollusks and crustaceans. This is manifested in their occurrence in winter. Commons are pretty much everywhere in salt water and fairly common in fresh water, as there is always something to eat.

Barrow's, on the other hand, are highly localized in salt water and quite scarce in fresh water. It makes sense; the mussel beds that Barrow's frequent are localized as well. Because they are more concentrated, you usually see Barrow's in larger flocks than Common. One place there are a lot of mussels is on clumps of pilings around docks and ferry landings, and those are the best places to look for Barrow's Goldeneyes, along with the Surf Scoters that take the same prey. The ducks have strong enough bills to be able to jerk mussels from the substrate!

Like most of our wintering waterfowl, these ducks pair in the winter, so by spring they are all in pairs, showy black and white males and more subdued brown and gray females. But there are still unmated males, so wherever goldeneyes hang out, watch for their spectacular courtship displays. The males throw their heads back while vocalizing and scoot forward on the water.

Both species nest in old woodpecker holes and tree crevices on freshwater lakes. Barrow's is fairly common on mountain lakes all across the Pacific Northwest, while Common is a more northerly species, relatively rare as far south as Washington.

Tuesday, April 3, 2012

The Snowy Owls (Bubo scandiacus) that came down to Washington this winter, which I have written about before, finally contributed some pellets to the cause of science.

Of course, you know what owl pellets are. Birds of prey, and actually quite a few other birds, eat a lot of stuff that doesn't make it through their digestive tract. Hair and feathers are difficult to digest, as are bones and mollusk shells. So even if they are broken into smaller pieces when eaten and crushed by heavily muscled gizzards, even the smaller pieces can't pass through the hindgut very well. Rather than sharp-pointed bones coming up one by one, they are coated in hair or feathers and barfed, urped, hurled, vomited and/or regurgitated back into the environment.

It's not easy to find these pellets unless you know right where the bird has been roosting. After they are produced, they get covered up by detritus, even blown around, and eventually decay into pieces. But they hold together for a while, and ornithologists have long used them to get a handle on the diet of birds such as hawks and, especially, owls. Snowy Owl pellets look like fuzzy three-inch cigars. It's been said there is nothing like a good cigar, but I personally prefer owl pellets.

Paul Bannick, well-known bird photographer and author of The Owl and the Woodpecker, recently sent me three pellets he picked up from one spot at Ocean Shores. At the museum, we soaked them in water and stirred them up until the feathers floated and the bones sank. We recovered a surprising amount of bones, arranged them by type, and identified them by comparing with our skeleton collection.

I had a pretty good idea what birds were out there, and it wasn't difficult to identify the majority of the bones as sandpiper bones. The only confusion would have been between Sanderling and Dunlin, both common birds in Grays Harbor. Sanderlings were common right where the owls were roosting, so I favored them. Sure enough, there were several lower mandibles present, and they clearly belonged to Sanderlings.

In total, at least five Sanderlings were present in these pellets, as indicated by counts of tibiae and tarsometatarsi, long, slender bones that were well represented because birds of prey tend to swallow legs of smaller birds whole. In addition to all the sandpiper bones, there were quite a number of larger bones. Many of them were broken up, but a few were intact, and two coracoids and a femur allowed identification as a Horned Grebe. Probably all the bones, including many vertebrae, were from the same bird.

I also examined single pellets from Sandy Point, near Bellingham, furnished by Isa Werny and Andrea Warner. They were mostly feathers, but one of them contained a few Horned Grebe bones, the other a few Bufflehead bones. The second pellet was found at the foot of a utility pole along with parts of a dead Bufflehead, making the identification easier. Both of these species are known Snowy Owl prey.

Snowy Owls are well known to subsist largely on water birds in the winter on our coast, and there wasn't a trace of a mammal in these five pellets. By now you may have figured out that ornithophagous = bird eating.

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About the Slater Museum

Our goals are to preserve and provide a collection of specimens to be used for research and education. Located in Tacoma, Washington, the Slater Museum is one of the region's significant repositories for bird, mammal, reptile, amphibian and plant specimens from the Pacific Northwest. In addition, we strive to educate the local community about nature and about the value of museums.